Vibration and pressure wave therapy for calf strains: a proposed treatment

Denne nevner også veldig mye interessant om Segmental Vibration Therapy, og benytter seg av en maskin som ligner Percussor. Nevner bl.a. at betennelses faktorer, som IL-6 og CRP, går ned


Calf (lower leg) strains have a variety of treatment regimens with variable outcomes and return to activity (RTA) time frames. These injuries involve disruption of portions or the entire gastrocnemius-soleus myo-tendinous complex. Conservative treatment initially consists of rest, ice, compression, elevation (RICE). Immediately following calf injury, patients can utilize cryotherapy, massage, passive range of motion, and progressive exercise. In general, Grade I through Grade III calf strains can take up to 6 weeks before the athlete can return to training. It can also involve the loss of more than 50% of muscle integrity. Recently, vibration therapy and radial pressure waves have been utilized to treat muscular strains and other myo-tendinous injuries that involve trigger points. Studies have suggested vibration therapy with rehabilitation can increase muscle strength and flexibility in patients. Segmental vibration therapy (SVT) is treatment to a more focal area. Vibration therapy (VT) is applied directly to the area of injury. VT is a mechanical stimulus that is thought to stimulate the sensory receptors, as well as decrease inflammatory cells and receptors. Therefore, VT could be a valuable tool in treating athlete effectively and decreasing their recovery time. The purpose of this paper is to give the reader baseline knowledge of VT and propose a treatment protocol for calf strains using this technology along with radial pressure waves.

Findings also showed a decrease in IL6 at five days after an increase at the first 24 hours as compared to the control group. There was a decrease in CRP and Histamine at five days. Broadbent et al. related the CPK findings were unclear4.

treatment showed increase ROM at the ankle, and increased hamstring flexibility compared to the post control treatment as well as baseline. There was also a decrease in stiffness at the ankle as well as the hamstring after SVT.


Focal vibration in neurorehabilitation.

Studien som går igjennom det meste av studier på hvordan vibrasjon påvirker nervesystemet og forskjellige sykdommer. Denne nevner bare rask vibrasjon, fra 60Hz og oppover. Konklusjonen er at vibrasjonsbehandling er en trygg, uten bivirkninger, lett å bruke og behagelig for klienten. Den bidrar med å redusere spastisitet (muskelsammentrekning), øker motorisk aktivitet (som bevegelse og balanse), og øker evnen til motorisk opplæring (f.eks. å gå etter en slagepisode).

Hele her:


During the last decade, many studies have been carried out to understand the effects of focal vibratory stimuli at various levels of the central nervous system and to study pathophysiological mechanisms of neurological disorders as well as the therapeutic effects of focal vibration in neurorehabilitation. This review aimed to describe the effects of focal vibratory stimuli in neurorehabilitation including the neurological diseases or disorders like stroke, spinal cord injury, multiple sclerosis, Parkinson’s’ disease and dystonia. In conclusion, focal vibration stimulation is well tolerated, effective and easy to use, and it could be used to reduce spasticity, to promote motor activity and motor learning within a functional activity, even in gait training, independent from etiology of neurological pathology. Further studies are needed in the future well-designed trials with bigger sample size to determine the most effective frequency, amplitude and duration of vibration application in the neurorehabilitation.


To studier på smertestillende effekt av Percussor

To studier forklarer det mye om hvordan percussorbehandling reduserer smerte, og bekrefter mine teorier som er beskrevet i artikkelen om Percussor behanding. Nevner at nerver i huden skaper en interaksjon mellom de to områdene av hjernen som involverer smerte og berøring. Distraksjon sier de ikke er en del av den smertereduserende effekten.

How does vibration reduce pain?


Cutaneous vibration is able to reduce both clinical and experimental pain, an effect called vibratory analgesia. The traditional explanation for this phenomenon is that it is mediated by lateral inhibition at the segmental (spinal cord) level, in pain-coding cells with center-surround receptive fields. We evaluated this hypothesis by testing for two signs of lateral inhibition-namely (1) an effect of the distance between the noxious and vibratory stimuli and (2) an inhibition-induced shift in the perceived location of the noxious stimulus. The experiment involved continuous ratings of the pain from pressure applied to the back of a finger, alone and in the presence of vibration delivered to sites on the palm of the hand both near to and far from the site of painful stimulation. Neither prediction of the segmental hypothesis was supported. There was also little evidence to support the view (widely held by subjects) that distraction is the primary mechanism of vibratory analgesia. The results are more consistent with a recently proposed theory of interactions between two cortical areas that are primarily involved in coding pain and touch, respectively.

Vibratory antinociception: effects of vibration amplitude and frequency.


The ability of cutaneous vibration to compromise detection of a nociceptive stimulus was examined in 2 sets of psychophysical experiments. The noxious stimulus was a 10-millisecond burst of radiant heat from a CO2 laser; at the near-threshold levels used it generally yielded a mild pricking sensation. In both experiments, the detectability (de′) of the laser was measured in the presence of different vibratory stimuli and in the absence of vibration. Periods of vibration lasted 10 seconds, bracketing the time of occurrence of the laser. Vibratory and laser stimuli were presented 2.3 cm apart on the dorsal surface of the forearm. Confidence rating procedures yielded receiver operating characteristic curves from which detectability of the laser was calculated. In an amplitude study, vibrations ranging from 10 to 45 dB above threshold were used; results indicated that nociceptive sensitivity gradually declined as vibration amplitude increased. In a frequency study, vibrations ranging from 20 to 230 Hz were used; all interfered with nociception. Combining the results of the 2 studies permitted the conclusion that signals in multiple vibrotactile channels are able to modulate nociception. No one mechanoreceptive channel appears to have a privileged role.

Vibration Therapy in Management of Delayed Onset Muscle Soreness (DOMS).

Svært interessant studie på hvordan vibrasjon (percussor) hjelper mot smerte og stølhet. Den snakker mest om whole-body-vibration, som f.eks. på en Vibroplate. Men de fleste fysiologiske effektene gjelder også for lokal vibrasjon som gis av en Percussor.

Hele studien her:


Both athletic and nonathletic population when subjected to any unaccustomed or unfamiliar exercise will experience pain 24-72 hours postexercise. This exercise especially eccentric in nature caused primarily by muscle damage is known as delayed-onset muscle soreness (DOMS). This damage is characterized by muscular pain, decreased muscle force production, reduce range of motion and discomfort experienced. DOMS is due to microscopic muscle fiber tears. The presence of DOMS increases risk of injury. A reduced range of motion may lead to the incapability to efficiently absorb the shock that affect physical activity. Alterations to mechanical motion may increase strain placed on soft tissue structures. Reduced force output may signal compensatory recruitment of muscles, thus leading to unaccustomed stress on musculature. Differences in strength ratios may also cause excessive strain on unaccustomed musculature. A range of interventions aimed at decreasing symptoms of DOMS have been proposed. Although voluminous research has been done in this regard, there is little consensus among the practitioners regarding the most effective way of treating DOMS. Mechanical oscillatory motion provided by vibration therapy. Vibration could represent an effective exercise intervention for enhancing neuromuscular performance in athletes. Vibration has shown effectiveness in flexibility and explosive power. Vibration can apply either local area or whole body vibration. Vibration therapy improves muscular strength, power development, kinesthetic awareness, decreased muscle sore, increased range of motion, and increased blood flow under the skin. VT was effective for reduction of DOMS and regaining full ROM. Application of whole body vibration therapy in postexercise demonstrates less pressure pain threshold, muscle soreness along with less reduction maximal isometric and isokinetic voluntary strength and lower creatine kinase levels in the blood.


Cutaneous Receptors Responses: The sensation of pressure and touch is masked during vibration [20], and also postvibration [21]. Some cutaneous mechanoreceptor afferents get aroused for many minutes postvibration [21] and this may be the physiological reason for the tingling sensation often experienced postvibration. On the basis of gate control hypothesis [22] we can infer that vibration strongly impacts affrents discharge from fast adapting mechanoreceptors and muscle spindles and hence become an effective pain reliever.

Pain Perception Responses: Vibration can be used as transcutaneous electrical nerve stimulation (TENS) [23] to reduce the perception of pain [7]. Passive vibration has reduced pain in 70% of patients with acute and chronic musculoskeletal pain [24] and passive 80 Hz vibration has been shown to reduce pain caused by muscle pressure [25]. More recent evidence suggests that pain perception in DOMS depends partly on fast myelinated afferent fibres, which are distinct from those that convey most other types of pain [26].

Lundeberg et al., concluded that vibration relieved pain by activating the large diameter fibres while suppressing the transmission activity in small diameter fibres [24,28].

Vibration therapy leads to increase of skin temperature and blood flow [30].


The meaning of mechanically produced responses

Fra 1994, forskeren Max Zusman. Nevner veldig mange interessante perspektiver på hvordan mekanisk stimuli (percussor, DNM, SI, osv) demper smerte.

Abstract: The precise source and cause of mechanically evoked sensory and motor responses can sometimes be surprisingly difficult to identify. Accurate interpretation of these responses may be confounded by peripheral as well as central nervous system mechanisms. Examples of such peripheral nervous system mechanisms likely to be of relevance to therapists have been selected from basic and clinical research. Symptomatic relief has been inferred to endorse the diagnostic specificity of mechanical stimulation. The extent to which this would be valid for relief acquired by neurological means is discussed in terms of endogenous pain inhibitory systems

Some degree of local inhibition with mechanical stimuli delivered directly to a pathological site may be mainly a consequence of supplementary input in large diameter cutaneous afferents. Unlike those afferents supplying deep tissue such as joint, muscle etc., small diameter cutaneous afferents appear to be largely impervious to mechanical sensitisation by chemical mediators of the inflammatory response (Handwerker and Reeh 1991).

Therefore, mechanical stimulus parameters which maximise large diameter afferent input from the skin and at the same time minimise sensitised small diameter afferent input from deep tissue such as joint, muscle etc. would be therapeutically effective

Spontaneously occurring clinically relevant symptoms and signs are ultimately a product of both peripheral and central nervous system mechanisms. As  such, they are complexly derived and displayed. Their true origin and significance are sometimes obscure and liable to misinterpretation. Rather than being invariably diagnostically definitive, provocative mechanical manoeuvres can compound these uncertainties. The provocative mechanical manoeuvres used by therapists are, neurologically speaking, relatively crude. They do not have the necessary specificity to always distinguish between pathologically and non pathologically involved tissues and sites, Since their specific systemic effects have not been investigated,  the responses produced with such stimuli are subject to variously influenced and informed interpretation.

The reasons for symptomatic relief produced asa result of these mechanical manoeuvres are not known for certain. Neurologically, this appears to involve inhibitions in the central nervous system. Input conveyed centrally by different classes of primary afferents stimulated at a variety of sites has the potential to produce therapeutically effective inhibitions. Mechanical provocation can confirm the presence of clinically relevant sensory and motor responses. However, understanding what these responses might actually mean in terms of their source and cause would frequently require additional input from the basic sciences.

Immunohistochemical demonstration of nerve endings in iliolumbar ligament.

Ett par studier som bekrefter at IL ligamentet er fullt av nervetråder. Viktig å vite for ligamentbehandlingen vi gjør på Verkstedet.

The function of iliolumbar ligament and its role in low back pain has not been yet fully clarified. Understanding the innervation of this ligament should provide a ground which enables formation of stronger hypotheses.

Iliac wing insertion was found to be the richest region of the ligament in terms of mechanoreceptors and nociceptors. Pacinian (type II) mechanoreceptor was determined to be the most common (66.67%) receptor followed by Ruffini (type I) (19.67%) mechanoreceptor, whereas free nerve endings (type IV) and Golgi tendon organs (type III) were found to be less common, 10.83% and 2.83%, respectively.

Those results indicate that ILL plays an important role in proprioceptive coordination of lumbosacral region alongside its known biomechanic support function. Moreover, the presence of type IV nerve endings suggest that the injury of this ligament might contribute to the low back pain.

Mer om IL ligamentet i denne studien:

Allodynia mediated by C-tactile afferents in human hairy skin

Viktig studie med alt om hudens c-fibre og deres relasjon til smerte (allodynia). Nevner at det er en samling av flere mekanoreseptorer i både muskel og hud som gir opphav smerte, ikke enkeltvis. 

We show that gentle tactile stimulation (vibration and brushing) of the hairy skin can exacerbate the underlying muscle pain (allodynia) evoked by infusion of hypertonic saline into the tibialis anterior muscle. This effect is dependent upon a low-threshold, mechanosensitive class of nerve fibres in the hairy skin known as C-tactile (CT) fibres. Knowledge of the role of CT fibres in allodynia increases our understanding of the mechanisms that underlie sensory-perceptual abnormalities – a common manifestation of clinical-pain states and neurological disorders.

We recently showed a contribution of low-threshold cutaneous mechanoreceptors to vibration-evoked changes in the perception of muscle pain. Neutral-touch stimulation (vibration) of the hairy skin during underlying muscle pain evoked an overall increase in pain intensity, i.e. allodynia. This effect appeared to be dependent upon cutaneous afferents, as allodynia was abolished by intradermal anaesthesia.
 Sustained muscle pain was induced by infusing hypertonic saline (HS: 5%) into tibialis anterior muscle (TA). Sinusoidal vibration (200 Hz–200 μm) was applied to the hairy skin overlying TA. Pain ratings were recorded using a visual analogue scale (VAS).
During tonic muscle pain (VAS 4–6), vibration evoked a significant and reproducible increase in muscle pain (allodynia) that persisted following compression of myelinated afferents. During compression block, the sense of vibration was abolished, but the vibration-evoked allodynia persisted.  In contrast, selective anaesthesia of unmyelinated cutaneous afferents abolished the allodynia, whereas the percept of vibration remained unaffected.
It is widely accepted that discriminative touch is mediated exclusively by large-diameter sensory fibres, whereas painful sensations are mediated by small-diameter fibres. Consistent with this view, selective microstimulation of a single large-diameter myelinated afferent in awake human subjects evokes a fundamental, innocuous (non-painful) sensation that has the quality of pressure, flutter or vibration according to the type of primary afferent excited (Ochoa & Torebjork, 1983Vallbo et al. 1984Macefield et al. 1990).
In addition to cutaneous nociceptors, which have high mechanical thresholds, there is another class of unmyelinated (C) fibre that has low mechanical thresholds. The existence of low-threshold unmyelinated afferents, termed C-mechanoreceptors, which respond to light touch of the skin, was documented long ago in the hairy skin of the cat and monkey (Zotterman, 1939Maruhashi et al. 1952Douglas & Ritchie, 1957Bessou et al. 1971). Although some investigators had suggested that C low-threshold mechanoreceptors (CLTMs) are vestigial (Kumazawa & Perl, 1977), recent studies have reported a class of unmyelinated fibres in the human hairy skin, known as C-tactile (CT) fibres, that responds to innocuous mechanical stimulation (Johansson et al. 1988Nordin, 1990Vallbo et al.1993).
The response properties of CT fibres have been described using a limited range of stimuli – most notably slowly moving, low-force, mechanical stimuli such as finger stroking and soft brushing (Nordin, 1990Vallbo et al. 19931999Lokenet al. 2009).
 It is this latter observation, together with the results of neuroimaging studies that have demonstrated that CT-mediated inputs project onto the insular cortex, which has underpinned the proposition of a CT-mediated emotional touch system (Olausson et al. 2002Cole et al. 2006;McGlone et al. 2007Olausson et al. 2008).  Intriguingly, in healthy subjects gentle brushing – known to elicit CT fibre responses – can evoke a neutral or even unpleasant sensation at the lowest brushing velocities (Loken et al. 2009), suggesting that gentle tactile stimulation can elicit opposing aspects of touch, i.e. predilection and aversion. A contribution of CT fibres to unpleasant touch has been suggested by recent work showing the activation of superficial dorsal horn neurons by gentle brushing of skin (Andrew, 2010Craig, 2010). Similarly, these fibres have been implicated in touch hypersensitivity after injury in mice (Seal et al. 2009).
In a recent pilot study we found that innocuous tactile stimulation (vibration) of hairy skin intensified the underlying muscle pain (allodynia), and that this effect appeared to be dependent upon cutaneous mechanoreceptors as the allodynia was abolished by intradermal anaesthesia (Nagi et al. 2009).
The ambiguity in the literature about the contribution of different fibre classes to allodynia may be attributed in part to the use of a single-compartment model in which innocuous and noxious stimuli are applied to the same or adjacent regions of skin. Such an approach can lead to uncertainty as to whether any change in pain perception reflects peripheral sensitization of nociceptive fibres and/or an altered central convergence of innocuous and noxious inputs.
The muscle is physically separated from the skin by sheet-like fascia and each is supplied by separate vascular and nerve supplies (O’Rahilly & Muller, 1986Berry et al. 1995;Salmons, 1995Gibson et al. 2009). Within the hairy skin it is known that such low-amplitude vibratory stimuli are preferentially encoded by hair follicle afferents at low frequencies (~5 Hz to 100 Hz) and by Pacinian corpuscle receptors at high frequencies (~50 Hz to 1000 Hz: Merzenich & Harrington, 1969Mahns et al. 2006). Although the response properties of CT fibres to vibratory stimulation remain untested, low-threshold mechanical sensitivity has been demonstrated using soft brushing (Vallbo et al. 1999Olausson et al. 2002;Loken et al. 2009).
We have shown that innocuous cutaneous vibration can increase the intensity of underlying muscle pain, induced by intramuscular infusion of hypertonic saline, and that this effect (i) persists during compression blockade of myelinated fibres but (ii) is abolished by selective anaesthesia of unmyelinated cutaneous afferents. Thus, vibration-evoked allodynia is evidently dependent upon intact C fibre inputs from the skin, and that these C-fibres have a low mechanical threshold (they responded to 200 μm vibration).
Vibration was described as non-painful by all subjects prior to the induction, and following cessation, of muscle pain. Our observations clearly implicate the mechanically sensitive C-tactile (CT) fibres in mediating this vibration-evoked allodynia. In contrast to earlier work, our psychophysical data indicate that the mechanical sensitivity of CT fibres need not be limited to slowly moving stimuli, as allodynia was evoked by vibration following blockade of myelinated afferents.
Using the same data presented by Loken et al.(2009) an alternative explanation can be advanced, namely that C-fibre and large-diameter afferents are activated in parallel during brush stroking, with a sense of pleasantness emerging when large-diameter responsiveness exceeds that of C-fibres.
In our study, brushing stimulation – at reportedly pleasant speeds – evoked allodynia during muscle pain. Thus, it is the concurrent activation of muscle nociceptors during hypertonic saline infusion and cutaneous mechanoreceptors during brushing (and vibratory) stimulation that leads to the allodynia.
In our study, brushing stimulation – at reportedly pleasant speeds – evoked allodynia during muscle pain. Thus, it is the concurrent activation of muscle nociceptors during hypertonic saline infusion and cutaneous mechanoreceptors during brushing (and vibratory) stimulation that leads to the allodynia. The use of differential nerve blocks to avoid the co-activation of multiple fibre classes during tactile stimulation – an ambiguity that has plagued earlier studies – confirms the role of CT fibres in mediating allodynia. Hence, it is the complement of active sensory fibres, rather than the activation of a single class of afferents, which determines the perceptual outcome of activating CT fibres. 
Neuroimaging studies have shown differential representation of pleasant and painful tactile stimuli in certain areas of the brain involved in emotional processing (insular, orbitofrontal and anterior cingulate cortices: Olausson et al. 2002Rolls et al. 2003). However, cortical activation evoked by a neutral tactile stimulus predominantly activates the discriminative-cognitive areas, the primary and secondary somatosensory cortices.
The qualia of touch may have evolved mainly in a social context to create a useful construct of the world, e.g. to predict whether the intent behind another’s action was benign or sinister; synthesized with the sense of ‘self’, these inputs subserve reflective self-awareness that characterizes humans as immensely social creatures (Ramachandran, 2004).

Tactile sensibility in the human hand: relative and absolute densities of four types of mechanoreceptive units in glabrous skin.

Nevner tetthet på sensoriske nerver i huden.

1. Single unit impulses were recorded with percutaneously inserted tungsten needle electrodes from the median nerve in conscious human subjects.
2. A sample of 334 low threshold mechanoreceptive units innervating the glabrous skin area of the hand were studied. In accordance with earlier investigations, the units were separated into four groups on the basis of their adaptation and receptive field properties: RA, PC, SA I and SA II units.
3. The locations of the receptive fields of individual units were determined and the relative unit densities within various skin regions were calculated. The over-all density was found to increase in the proximo-distal direction. There was a slight increase from the palm to the main part of the finger and an abrupt increase from the main part of the finger to the finger tip. The relative densities in these three regions were 1, 1.6, 4.2.
4. The differences in over-all density were essentially accounted for by the two types of units characterized by small and well defined receptive fields, the RA and SA I units, whereas the PC and SA II units were almost evenly distributed over the whole glabrous skin area.
5. The spatial distribution of densities supports the idea that the RA and SA I units account for spatial acuity in psychophysical tests. This capacity is known to increase in distal direction along the hand.
6. On the basis of histological data regarding the number of myelinated fibres in the median nerve, a model of the absolute unit density was proposed. It was estimated that the density of low threshold mechanoreceptive units at the finger tip is as high as 241 u./cm2, whereas in the palm it is only 58 u./cm2.

A model accounting for effects of vibratory amplitude on responses of cutaneous mechanoreceptors in macaque monkey

Nevner vibrasjonens effekt på alle sensoriske nerver i huden. Gammel studie fra 80-tallet.

1. A mechanoreceptor model, developed in the preceding paper (Freeman & Johnson, 1982), was used to study the effects of vibratory intensity and frequency on the responses of slowly adapting, rapidly adapting and Pacinian afferents in monkey hairless skin. As in the previous paper almost all of the response properties studied here were accounted for by the equivalent circuit model; changes in membrane time constant and amplitude sensitivity accounted for the differences between the three mechanoreceptive fibre types.

2. The stimulus—response function of primary concern was the relationship between impulse rate and vibratory amplitude. This relationship had the same general form in each of the three fibre types. Amplitudes, I, less than I0 produced no impulse on any stimulus cycles. Amplitudes greater than I1produced one impulse on every cycle. As I rose from I0 to I1 the impulse rate rose monotonically from 0 to 1 impulse/cycle. For each fibre type the form of this ramp depended on the stimulus frequency.

3. At stimulus frequencies low in the frequency range of each fibre type the (I0, I1) ramp tended to be steep and sigmoidal in shape. Two or more impulses occurred on some cycles and none on others.

4. At intermediate frequencies the (I0, I1) ramps became linear with at most one impulse on each cycle. A short plateau appeared at 0·5 impulses/cycle (i.e. there was a range of intensities yielding one impulse on alternate cycles). All of these response properties at low and intermediate frequencies were explained by the model.

5. At higher frequencies the (I0, I1) ramps became shallower and developed discontinuities in slope at impulse rates of 0·5 impulses/cycle. At stimulus frequencies greater than 20 Hz for SAs and RAs, the upper segment of the (I0, I1) slope became steeper. For frequencies greater than 80 Hz, the upper segments of the Pacinian (I0, I1) slopes were shallower than the lower segments. These effects suggested transient periods of hyperexcitability following each action potential, and reductions in sensitivity due to high impulse rates, respectively.

6. The model’s membrane time constant was adjusted to match the observed reduction in the (I0, I1) slope with increasing stimulus frequency. The time constants required for least-squares fitting were 58, 29 and 4·2 msec for slowly adapting, rapidly adapting and Pacinian afferents, respectively; these values are of the same order as those obtained in the preceding paper.

7. Receptor sensitivity varied across the frequency spectrum, slow adaptors being most sensitive at low frequencies, rapidly adapting units at mid-range, and Pacinians at the high frequencies. According to the model, the high frequency roll-off in a receptor’s tuning curve is due to the current integrating properties of receptor membrane, and the low frequency roll-off is due to a high pass filter, presumably mechanical, situated in the tissues between the stimulus probe and receptor membrane.

8. Impulse phase advances with increasing stimulus intensity in both receptor and model. The ability of the model to fit both the rate—intensity function and phase advance functions in individual receptors is demonstrated.

The Effect of Surface Wave Propagation on Neural Responses to Vibration in Primate Glabrous Skin

Studie som nevner at vibrasjon sprer seg i huden og forsterker signalene opp til hjernen. Men har bare 1 mm kontaktflate og forholder seg til høy frekvens (opp til 400 Hz)og pacini celler. Mye interessant likevel.

«First, we find that these waves substantially amplify the neural response to the stimulus»

«Second, we show that surface waves result in a reduction of the temporal patterning in the response of afferent populations, particularly at frequencies over 200 Hz, but the degree of temporal blurring is relatively small compared to that observed in the response of S1 neurons.»

«Third, despite these two factors, the structure of the waveform is well preserved in the form of the surface waves, suggesting that surface waves should enhance the perception of simple and complex skin oscillations.»

Because tactile perception relies on the response of large populations of receptors distributed across the skin, we seek to characterize how a mechanical deformation of the skin at one location affects the skin at another.

First, we show that a vibration applied to the fingertip travels at least the length of the finger and that the rate at which it decays is dependent on stimulus frequency.

We show that this skin resonance can lead to a two-fold increase in the strength of the response of a simulated afferent population.

Second, the rate at which vibrations propagate across the skin is dependent on the stimulus frequency and plateaus at 7 m/s. The resulting delay in neural activation across locations does not substantially blur the temporal patterning in simulated populations of afferents for frequencies less than 200 Hz, which has important implications about how vibratory frequency is encoded in the responses of somatosensory neurons.

Third, we show that, despite the dependence of decay rate and propagation speed on frequency, the waveform of a complex vibration is well preserved as it travels across the skin. Our results suggest, then, that the propagation of surface waves promotes the encoding of spectrally complex vibrations as the entire neural population is exposed to essentially the same stimulus.